存在文件时找不到VirtualFileResult文件

Question

也许我不了解VirtualFileResult是什么，但是我不确定为什么文件存在时为什么抛出FileNotFoundException。这是代码：

if (System.IO.File.Exists(fileName))
{
    FileInfo info = new FileInfo(fileName);

    return File(fileName, FileUtility.GetContentType(fileName), info.Name);
}

（编辑：（FileUtility.GetContentType正确）返回文件的Mime类型，以我为例"application/pdf"。）

这是我得到的异常：（我删除了文件路径）

System.IO.FileNotFoundException: Could not find file: [file path removed]
File name: '[file path removed]'
   at Microsoft.AspNet.Mvc.VirtualFileResult.<WriteFileAsync>d__11.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeResultAsync>d__56.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeResultFilterAsync>d__55.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeAllResultFiltersAsync>d__54.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeResourceFilterAsync>d__49.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.AspNet.Mvc.Controllers.FilterActionInvoker.<InvokeAsync>d__44.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Mvc.Infrastructure.MvcRouteHandler.<RouteAsync>d__6.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Routing.Template.TemplateRoute.<RouteAsync>d__27.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Routing.RouteCollection.<RouteAsync>d__9.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.IISPlatformHandler.IISPlatformHandlerMiddleware.<Invoke>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Diagnostics.StatusCodePagesMiddleware.<Invoke>d__3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.AspNet.Diagnostics.DeveloperExceptionPageMiddleware.<Invoke>d__7.MoveNext()

即使对文件是否存在进行了明确检查，它似乎仍在出错。我也可以手动确认文件存在。

也许我不明白什么是VirtualFileResult（File方法返回此结果）。在这里的文档中，它并没有真正描述它是什么。

我正在使用ASP.NET 5 RC1。

Answer 1

您正在寻找的方法是PhysicalFile()：

return PhysicalFile(fileName, FileUtility.GetContentType(fileName), info.Name);

当心，不要使用调用者提供的路径。

Answer 2

该类VirtualFileResult需要在其构造函数中提供文件的虚拟路径。
这意味着您需要提供相对于该文件夹的路径，wwwroot因为它使用 HostingEnvironment 的WebRootFileProvider.

    private IFileProvider GetFileProvider(IServiceProvider requestServices)
    {
        if (FileProvider != null)
        {
            return FileProvider;
        }

        var hostingEnvironment = requestServices.GetService<IHostingEnvironment>();
        FileProvider = hostingEnvironment.WebRootFileProvider;

        return FileProvider;
    }
}

检查github上的代码